An example of the lens-tube-rotation-type image pickup apparatus in which a lens tube rotates is a dome-type monitoring camera set on a ceiling, wall, and the like in a building. Dome-type cameras are set for the purpose of securing safety, improving services, and the like in hospitals, hotels, department stores, and the like and perform monitoring using photographed images. Specifically, the dome-type cameras are each obtained by accommodating an optical block constituted of a lens and an image pickup block constituted of an image pickup device in the lens tube, attaching the lens tube so as to be rotatable in both the horizontal (hereinafter, referred to as “pan direction”) and vertical directions (hereinafter, referred to as “tilt direction”), and covering an outer circumference of a movable area of the lens tube by a dome-type cover. Image pickup signals from the image pickup block are connected to a monitor in a monitoring room via a coaxial cable.
Here, the dome-type cameras as described above are each set by being fixed to a ceiling, wall, and the like of a building by an embedded bracket after the coaxial cable is connected to a back surface thereof. Next, a lens is adjusted to a predetermined orientation (direction and angle) by an angle adjustment mechanism of the lens tube, and focus and zoom of the lens are set. At this time, the setting is performed while looking at a monitor image at a setting location and checking an image pickup direction and range using a portable monitor. Finally, dust is prevented by attaching a dome-type cover on a front surface, and a series of setting tasks is ended.
As described above, when setting the dome-type camera, the lens orientation is set by adjusting an angle of the lens tube. A technique that uses a ball joint as the angle adjustment mechanism is known. Specifically, this technique enables the lens tube to be rotationally adjustable in the pan direction and tilt direction by a rotating sphere section provided at a base end of the lens tube and the rotating sphere section to be fixed to a supporting member provided on a pedestal by a retaining member (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-open No. 2000-156806